Skiving machines



April 1960 R. GEHRER ET AL 2,932,372

SKIVING MACHINES Filed Sept. 18, 1956 5 Sheets-Sheet l April 12, 1960 R.GEHRER ETAL 7 2,932,372

SKIVING MACHINES Filed Sept. 18, 1956 :5 Sheets-Sheet 2 IN V EN TOR!April 12, 1960 GEHRER ETAL 2,932,372

SKIVING MACHINES Filed Sept. 18, 1956 3 Sheets-Sheet 3 INVENTORS SKIVINGMACHINES Rudolf Gehrer, Stuttgart-Bad Cannstatt, and Dieter Braun,Stuttgart-Heumaden, Germany, assignors to Firma Fortuna-WerkeSpezialmaschinenfabrik A.-G., Stuttgart-Bad Cannstatt, Germany AApplication September 18, 1956, Serial No. 610,510 Claims priority,application Germany September 22, 1955 13 Claims. (Cl. 192-=-18) Thepresent invention relates to machines for cutting or trimming sheetmaterial, such as skiving machines used in cutting the edges of piecesof leather.

In skiving machines it is customary for the operator to hold the sheetmaterial on a feed roller while moving sheet material with respect tothe annular cutting edge of a bell-shaped cutter. Certain workpieceshave special curvatures which are particularly difiicult to skivebecause the feed roller and skiver rotate at speeds which are maintainedat a predetermined relationship with respect to each other. Inconventional machines these speeds are constant or the speeds of thefeed roller and skiver increase and decrease together while maintainingthe same relationship. Thus, it becomes necessary when handling certainworkpieces for the operator to hold the workpieces in such a manner thatthe feed roller slips with respect thereto, and only poor results can beobtained in this way. Moreover many pieces are spoiled and can be usedonly as waste as a result of this drawback.

One of the objects of the present invention is to provide a skivingmachine in which the speed of rotation of the feed roller can beaccurately and conveniently regulated by the operator without alteringthe speed of rotation of the skiver.

Another object of the present invention is to provide a skiving machinein which the speed of rotation of the feed roller can be independentlyregulated without the use of complex expensive installations such asgear reduction assemblies or the like.

An additional object of the present invention is to provide a structurecapable of providing a convenient accurate regulation of the speed ofrotation of the feed roller particularly at the lower speeds thereof.

A further object 'of'the present invention is to provide a singlecompact simple assembly capable of being used on the one hand toregulate the speed of rotation of the feed roller'and on the other handto brake the rotation of the feed roller.

7 It is also an object of the present invention to providean operatingstructure, capable of being actuated by the operator to regulate thespeed of rotation of the feed roller, which can be adjusted convenientlyto the needs of the particular operator so as to be accessible to a footof the operator, for example, and which at the same time will reliablyremain in its adjusted position.

With the above objects in view the present invention mainly consists ofa skiving machine which includes a feed roller drive shaft for drivingthe feed roller so that the latter can move a workpiece with respect toa skiver. This drive shaft is supported for rotation about its axis by asuitable support means. A-driving pulley is coaxial with and freelyrotatable with respect to the drive shaft, and a stationary platesurrounds the drive shaft and is nited States Patent 2,932,372 PatentedApr. 12, 1960 first disc and the stationary plate and has a side facedirected toward and located adjacent a side face of this plate, one ofthe latter side faces also carrying a layer of a material of a highcoeflicient of friction. A motion transmitting member is connected tothe shaft for rotation therewith 'but is free to move axially withrespect thereto, and this motion transmitting member is located betweenthe first and second discs and is axially shiftable with respect to thelatter while these discs are constrained to rotate with the motiontransmitting member. This latter member is operatively connected to thediscs in such a way that when the motion transmitting member is movedtoward the pulley the first disc is moved by the motion transmittingmember toward the pulley, and when the motion transmitting member ismoved toward-the stationary plate the second disc also moves toward thestationary plate. Thus, in one direction of movement the motiontransmitting member provides driving engagement between the pulley andfirst disc so that the pulley rotates the shaft, and in the oppositedirection of axial movement the motion transmitting member causes thesecond disc to cooperate with the stationary plate through the layer ofhigh friction material therebetween to brake the rotation of the shaft.A special spring is located between the motion transmitting member andthe first disc in order to enable the speed of rotation of the feedroller drive shaft to be very accurately regulated.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation,

together with additional objects and advantages thereof, will be bestunderstood from the following description I of specific embodiments whenread in connection with spaced axially from the pulley. A first discfreely surthe accompanying drawings, in which:

Fig. 1 is a side elevational view of a machine according to the presentinvention;

Fig. 2 is a partly sectional plan view of the machine taken along lineII-ll of Fig. 1 in the direction of the arrows;

Fig. 3 is a fragmentary, sectional view on an enlarged scale showingdetails of the structure of the invention, Fig. 3 being taken along lineIII-III of Fig. 2 in the direction of the arrows;

Fig. 4 is a fragmentary sectional view showing part of the structurewhich is also shown in Fig. 3 at a scale greater than that of Fig. 3,the structure of Fig. 4 being shown in one position above the horizontalcenter line of Fig. 4 and in another position below this center line;

Fig. 5 graphically illustrates the operation and characteristics of aspring'which forms part of the present invention;

Fig. 6 is a fragmentary, sectional view taken along line VI-VI of Fig. 3in the direction of the arrows; and

Fig. 7 is an exploded, perspective view showing some of the membersillustrated in Fig. 3.

As may be seen from Fig. 1, the machine includes a suitable frame 1which supports a work table 2. A motor 3 is carried by the table 2 atthe underside thereof, and this motor drives a pulley belt 4 whichinturn drives the pulley 5. The belt 4 is shown in dot-dash lines inFig. 2 which also shows the shaft 6 which rotates together with thepulley 5. The shaft 6 is supported for rotation about its axis insuitable bearings, and at its left end, as viewed in Fig. 2, the shaft 6carries the skiver 7 which rotates with the shaft 6, so that in this waythe skiver is driven. The skiver is in the form of a hell or cup-shapedmember having a left. an

nular edge, as viewed in Fig. 2, which forms thecutting edge of theskiver.

As may be seen from Fig. 2, the pulley 5 is fixed coaxially to a steppedpulley 8 which rotates together with pulley and the shaft 6, and a belt9 transmits the rotation of the pulley 8 to the pulley 10. Referring nowto Fig. 3, it will be seen that the pulley 10 is supported for freerotation about its axis by a ball bearing 11 which is mounted on the endportion 12 of an elongated feed roll drive shaft 13 which drives thefeed roll 14 shown in Fig. 2. The feed roll 14 is supported for rotationabout its axis by any suitable unillustrated structure, and the axis ofthe feed roll 14 is perpendicular to that of the shaft 6 and skiver 7.As is well known in the art, the sheet material such as leather isplaced on the feed roll 14 which moves it with respect to the skiver 7in such a way that the desired cutting of the sheet material at the edgethereof is obtained.

The housing 15 fixedly carries a tubular member 16 (Fig. 3) throughwhich the shaft 13 freely passes, and

the left end of the tubular member 16, as viewed in Fig. 3, is enlargedand receives a ball bearing 17 which supports the shaft 13 for rotationabout its axis, so that parts 15-17 form a support means which supportsshaft 13 for rotation. The outer race 18 of the bearing 17 is pressed tothe right, as viewed in Fig. 3, against a shoulder in the interior ofthe tubular bearing housing 16 by a cap nut 19 threaded onto the leftend of housing 16, as viewed in Fig. 3, and having a left wall whichbears against the left end face of the race 18, this left wall of thecap nut 19 being formed with an opening through which the shaft 13freely passes.

The shaft 13 is formed adjacent its end portion 12 with an elongated,axially extending cutout 20 defined in part by a pair of opposedparallel planar surfaces which extend parallel to the axis of shaft 13.These surfaces are slidably engaged by a pair of outer parallel sidefaces of a rectangular block 21 which forms a motion transmitting memberand which extends through and beyond the cutout 20 in a directiontransverse to the axis of shaft 13. As is apparent from Fig. 3, thewidth of the motion transmitting member 211 is considerably less thanthe length of the cutout 20 so that the member 21 is free to shiftaxially with respect to shaft 13 while being constrained to rotatetherewith.

An annular layer 22 of a material of a high coefiicient of friction,such as the material used for brake shoes,

is carried by a disc 23 at the right side face thereof as viewed inFigs. 3 and 4. The disc 23 is formed with an opening through which theshaft 13 freely passes so that were it not for member 21 the disc 23would turn freely with respect to shaft 13. The disc 23 is coaxial withshaft 13 and has an elongated hub extending from the ,left side face ofthe disc 23, as viewed in Figs. 3 and 4.

This elongated hub of disc 23 and a portion of the latter adjacent thehub thereof are formed with cutouts defined by surfaces which formcontinuations of the opposed parallel surfaces of cutout 20 which areslidably engaged by opposed side faces of member 21, respectively, sothat these side faces of member 21 also slidably engage the opposedparallel surfaces of disc 23 which define the cutouts thereof shown inFigs. 3 and 4. Thus, the elongated tubular hub of disc 23 is formed witha pair of opposed parallel slots through and beyond which opposite endportions of member 21 freely pass, respectively, and the part of disc 23adjacent its hub is formed with an elongated rectangular cutout forminga continuation of the hub slots and extending across the .bore of disc23 through which shaft 13 passes, the right edge portion of member 21,as viewed in Figs. 3 and 4, being located in this rectangular cutout ascan be best visualized from Figs. 6 and 7. It is apparent that elements21 and 23 are constrained to rotate with shaft 13 but are free to shiftaxially therealong. Theleft end wall of cap nut 19 forms a stationaryplatewhose outer left side face, as viewed in Figs. 3 and 4, cooperateswith the layer 22 to act as a brake for braking the irotation of theshaft l3.

A leaf spring 24 having special spring characteristics described belowalso extends through and beyond the left face of the motion transmittingmember 21, as viewed in Figs. 3 and 4. The leaf spring 24 is ofsubstantially rectangular configuration and has its free endsrespectively located in a pair of elongated axial cutouts formed at theinner periphery of an annular disc 26 which carries at its left face, asviewed in Figs. 3 and 4, an annular layer 25 of a material of a highcoefficient of friction which may be the same material as that used forthe layer 22. The elongated opposed axial cutouts at the inner peripheryof the disc 26 are rectangular in cross section and slidably receive theupper and lower left corner portions of the member 21, as viewed inFigs. 3 and 4, so that the disc 26 is constrained to rotate with themember 21 while being axially shiftable wtih respect to shaft 13, andmembers 21 and 26 are also axially shiftable with respect to each other.

The left end face of the inner race 27 of the bearing 17 serves as anabutment for the right end of a coil spring 28, as viewed in Figs. 3 and4, this coil spring 28 being coiled about the shaft 13 and having itsleft end in engagement with the right side face of disc 23, so that thespring 28, which is under compression, urges the disc 23 together withmotion transmitting member 21 to the left, as viewed in Figs. 3 and 4,away from cap nut 19.

The right end face of the inner race 29 of the bearing 11 serves as anabutment for the left end of a coil spring 30 which is coiled about theshaft 13 and which bears with its right end against the left end face ofthe hub of the disc 23, as viewed in Figs. 3 and 4, this spring 30 beingweaker than the spring 28. This inner race 29 slidably engages the shaft13 and is urged by the spring 30 against a nut 31 threadedly carried bythe end portion 12 of shaft 13. Thus, when the shaft 13 is stationarythe nut 31 may be turned to adjust the distance between .pulley 10 anddisc 26, and spring 30 reliably maintains the bearing 11 in its adjustedaxial position where its inner race 29 abuts against the nut 31.

The housing 15 which is carried by the table 2, as indicated in Fig. 3,fixedly carries a bracket 32 which in turn carries a pivot pin on whicha bell crank 33 i tgrnable. As is apparent from Fig. 3, the bell crank33 has an upwardly extending arm and a substantially horizontallyextending arm considerably longer than the upwardly extending arm. Thelatter arm is provided at its free end with a threaded bore whichthreadedly receives a threaded stud 34 which carries a lock nut 35.Thus, after the stud 34 is turned so that its right end, as viewed inFig. 3, extends to a desired extent beyond the upper free end of theshorter arm of bell crank 33, the lock nut 35 is turned to fixedlymaintain the stud 34 in its adjusted position. The right free end of thestud 34 engages the left end of an elongated push rod 36 which extendsslidably through an axial bore formed in the end portion 12 of shaft 13and communicating with the cutout 20 thereof. The right end of push rod36, as viewed in Fig. 3, bears directly against the left face of theleaf spring 24, as viewed in Figs. 3 and 4. A coil spring 37 iscompressed between a stationary member fixed to housing 15 and thelonger arm of hell crank 33 so that this coil spring tends to turn thebell crank in a clockwise direction, as viewcd in Fig. 3. Coil spring 37is considerably stronger than the total of the forces of the springs 24and 28 which oppose the spring 37.

The free end of the longer arm of the bell crank 33 fixedly carries theball member of a ball and socket joint 50 whose socket member is fixedto an elongated rod 38 composed of tubular sections which aretelescopically slidable with respect to each other so that the length ofthe rod 38 may be adjusted. The upper portion of the rod 38 extendsfreely through an opening of the table 2, as is apparent from Fig. 3,and a manually turnable screw member 40 may be loosened when it isdesired to adjust the length of the rod 38 and may then be tightened tomaintain the rod 38 .at its adjusted length, matically illustrated inFig. .1. The bottom end of the rod 38 is pivotally connected to a pedalmeans which includes a base plate 39 resting directly on the floor. Thebase plate 39 carries at its top face a stationary catch member 41 whichcooperates with a springy catch member 42 carried by the underside'ofthe tiltable pedal 43 which is urged to turn in a counterclockwisedirection, as viewed in Fig. 1, by a leaf Spring 44 located between andbearing against pedal 43 and base plate 39. A hinge 45 is locatedbetween and connected to pedal 43 and base plate 39 to provide theturnable mounting of pedal 43 on base plate 39. When theoperator hasturned the pedal 43 in a clockwise direction, as viewed in Fig. 1through an angle suflicient to cause the springy catch member 42 tolatch with the stationary catch member 41, these catch members cooperateto maintain the pedal 43 in the position which it has been turnedagainst the force of spring 44 and spring 37. It will be noted that thespring 37 urges the rod 38 downwardly at all times and that this rod 38is always under compression. As a result the pedal means is continuallypressed against the floor. With this arrangement the operator can adjustthe length of rod 38 so as to locate the pedal means at the mostcomfortable position and the pedal means will not shift from thisposition because it is continually pressed against the floor.

As may be seen from-Fig. 2, the feed roll drive shaft 13 fixedly carriesa worm 46 which is coaxial with the feed roll drive shaft 13 and whichrotates therewith, and the as is diagramworm 46 turns a worm wheel 47fixedly carried by a shaft 48 supported by any suitable bearingstructure for rotation about its axis. The end of shaft 48 distant fromworm wheel 47 is connected to a universal joint which is in turnconnected to a rod 49 whose end distant from the shaft 48 is connectedby another universal joint to an end of the feed roll 14, so that inthis way the driveis transmitted from the shaft 13 to the feed'roll 14.

The above described structure operates as follows: 7

' The parts are shown in Figs. 1 and 3 in their rest po sition. In thisposition of the parts the layer 25 is spaced from the right face of thepulley 10, as viewed in Fig. 3, so that the latter does not transmit thedrive to the shaft 13. Furthermore, the spring 37 causes the push rod 36to press leaf spring 24 against motion transmitting member 21, and theforce of spring 37 is thus transmitted to the disc 23 to press the layer22 against the stationary cap nut 19 so that the shaft 13 is braked andstopped, spring 37 being stronger than the total forces of springs 24and 28.

When the operator wishes to start the rotation of feed roll 14, skiver 7and pulley rotating continuously during operation of the machine, heturns the pedal 43 in a clockwise direction, as viewed in Fig. 1, so asto raise the rod 38 and turn the bell crank 33 in a counterclockwisedirection, as viewed in Fig. 3, against the force of spring 37 tocompress the latter further. This'action frees the discs 23 and 26 tothe influence of springs 28 and 24, respectively, the spring 28 being somuch stronger than the spring 30 that the latter functions principallyto maintain the race 29 against the nut 31. Thus, the disc 23 shifts tothe left to move the layer 22 away from cap nut 19 and the disc 26 movestoward the pulley 10 so that the layer 25 engages the right side face ofpulley 10, as viewed in Fig. 3, and in this way a drive is transmittedto the shaft 13 which rotates together with the pulley 10 when the pedal43 is fully depressed and the spring 37 is compressed sufiiciently toeliminate its influence on the discs 23 and 26. When the layer 25 firstengages the pulley 10 there is a slippage between these elements so thatthe shaft 13 at first rotates at a speed less than the pulley 10. Whenthe operator Wishes to stop the rotation of the feed roll 14, he presseswithhis toe against the left end of pedal 43, as viewed in Fig. 1, so asto turn the pedal in a counterclockwise direction,

and it is only necessary for the operator to apply suificient force torelease catch member 42 from catch member 41, and then the spring 37expands and automatically returns the parts to the position where therotation of shaft 13 is braked and stopped. It will be noted that withthe structure of the invention the energy for maintaining the parts bothin the position where the shaft 13 is driven and in the position whereit is stopped is derived solely from the springs.

The distance through which the disc 26 shifts axially from the time whenthe layer 25 first engages the pulley 10 until the time when the layer25 is pressed forcefully against the pulley 10 to transmit the drivewithout slip is quite small and is indicated in Fig. 4 at S If thespring 24 were omitted and the disc 26 shifted directly with member 21,it would be necessary for the operator to actuate the pedal in a veryprecise manner so as to maintain the layer 25 somewhere in the range Sto 'pro vide a desired speed of rotation of the feed roll less than itsfinal operating speed. Moreover, with a skiving machine it isparticularly desirable to maintain the feed roll 14 at speeds within thelower range of the speeds of rotation of the feed roll 14. It isapparent that without the spring 24 it would be extremely diflicult tocontrol the speed of the feed roll at all, and it would be impossible toprecisely maintain the feed roll at a relatively low speed of rotation.The spring 24 is carefully chosen so as to eliminate these drawbacks.

As may be seen from Fig. 4, during the time that the disc 26 shiftsaxially through the distance S the motion transmitting member 21 acts onthe spring 24 while moving through the distance 8; which is many timesgreater than the distance S In actual practice this latter distance maybe only a fraction of a millimeter, so that the spring 24 provides ameans for accurately controlling the engagement between pulley 10 andlayer 25. Y

The graph of Fig. 5 illustrates the operation of the spring 24 which mayhave a length of 30 millimeters and which may be cut from a strip ofspring steel 4 mm. wide and 0.5 mm. thick. The characteristic of theleaf spring 24 is not a straight line. The distance S indicates themovement of the spring from the position thereof at the upper part ofFig. 4'where the free ends of the spring curve to the left to theposition thereof at the lower part of Fig. 4 where the ends of thespringare clamped between elements 21 and 26 and where the centralportion of the spring bulges to the left. The characteristic of thespring 24 is such that'during approxim*ately'% of its movement, asrepresented by the distance S it causes the layer 25 to be pressedagainst the pulley 10 with only /s of the final pressure so that duringthis bi of the movement of the spring 24 the speed of rotation of theshaft 13 reaches only /5 of its final speed of rotation shown at n inFig. .5. his during the last & of the movement of'the spring 24 that thespeed ofrotation of shaft 13 increases from /5 of its final'speed up toits final speed. As a result it is possible for the operator to veryprecisely control the speed of rotation of the shaft 13 in the lowerfifth of its range of speeds, and this is particularly important for askiving machine. This arrangement may be contrasted with an; arrangementwhere a conventional coil spring having a straight line characteristicis substituted for the leaf spring. Such a straight line characteristicis shown in Fig. 5, and with such a spring it is apparent that Vs of thefinal speed of rotation of the shaft 13 isobtained when the spring iscompressed through only relatively short distance S so that very poorcontrol in the lower range of speeds can be provided with a springhaving a straight line characteristic. Thus, the use of a spring havingthe characteristic of the spring 24 as described above is ofconsiderable importance. The distance S is approximately /5 of the totaldistance S while the distance S is approximately of this total distance.

As an example of the advantages derived from this 7 structure, if itis.assumed that the pedal 43 turns through a total angle of 20, thenwith the above described leaf spring 24 the pedal can be turned through18 to'control the speed of rotation of the feed roll 14 anywhere withinthe lower fifth of its range of speeds, while the last two degrees ofturning of the pedal increases the speed of the feed roll from /5 of itsfinal speed to its final speed.

-It will be noted that the structure described above is relativelysimple and at the same time renders it possible to control the feed rollindependently of the shiver. Furthermore, a glance at Fig. 3 will showthat the structure for connecting the drive to the shaft 13 and forbraking theshaftis in the form of a single unitary assembly which isextremely compact and which is carried by the shaft 13 itself.

It will be understood that each of the elements described above, ortwoor more together, may also find a useful application in other types ofsheet material cutting machines differing from the types describedabove.

While the invention has been illustrated and described as embodied inskiving machines, it is not intended to be limited to the details shown,since various modifications and structural changes may be made withoutdeparting in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gistofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharac teristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence ofthe'following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a skiving machine, in combination, a drive shaft adapted to drivea feed roll which feeds a workpiece with respect to a skiver; supportmeans supporting said drive shaft for rotation about its axis; a pulleycoaxial with and freely turnable with respect to said shaft; a discmember and a block member coaxial with said shaft and being axiallyshiftable with respect to each other while constrained to rotatetogether, one of said members being axially shiftable with respect tosaid shaft while being constrained to rotate therewith, said disc memberhaving a side face directed toward and located adjacent a side face ofsaid pulley; a layer of a material of a high coefficient of frictioncarried by one of said side faces so that when the other of said sidefaces presses against said layer the rotation of said pulley will betransmitted to said disc member so as to rotate said shaft; and springmeans located between and freely abutting against said members andurging said block member with respect to said disc member in a directiondirected away from said pulley, so that when said block member is movedtoward said pulley the pressure of said other side face against saidlayer will be determined by the extent to which said spring means iscompressed and independent of any movement of said disc member towardsaid side face of said pulley.

2. .In a machine, in combination, a drive shaft; support meanssupporting said drive shaft for rotation about its axis; a pulleycoaxial with and freely turnable with respect to said shaft; a discmember and a block member coaxial with said shaft and being axiallyshiftable with respect to each other while constrained to rotatetogether, one of said members being axially shiftable with respect tosaid shaft while being constrained to rotate therewith, said disc memberhaving a side face directed toward and located adjacent a side face ofsaid pulley; a layer of a material of a high coetficient of frictioncarried by one of said side faces so that when the other of said sidefaces presses against said layer the rotation of said pulley will betransmitted to said disc member so as to rotate said shaft; and springmeans located between and freely abutting against said members andurging said block member with respect to said disc member in a directiondirected away from said pulley, so that when said block member is movedtoward said pulley the pressure of said other side face against saidlayer will be determined by the extent to which said spring means iscompressed, said spring means having a characteristic which graduallyincreases the pressure of said other side face against said layer duringthe greatest part of the compression of said spring means and whichsuddenly increases said pressure to its final value during a finalrelatively small fraction of the compression of said spring means.

3. In a machine, in combination, a drive shaft; support means supportingsaid drive shaft for rotation about its axis; a pulley coaxial with andfreely turnable with respect to said shaft; a disc member and a blockmember coaxial with said shaft and being axially shiftable with respectto each other while constrained to rotate together, one of said membersbeing axially shiftable with respect to said shaft while beingconstrained to rotate therewith, said disc member having a side facedirected toward and located adjacent a side face of said pulley; a layerof a material of a high coefiicient of friction carried by one of saidside faces so that when the other of said side faces presses againstsaid layer the rotation of said pulley will be transmitted to said discmember so as to rotate said shaft; and spring means located between andfreely abutting against said members and urging said block member withrespect to said disc member in a direction directed away from saidpulley, so that when said block member is moved toward said pulley thepressure of said other side face against said layer will be'determinedby the extent to which said spring means is compressed, said springmeans being in the form of a leaf spring having a characteristic whichgradually increases the pressure of said other side face against saidlayer during the greatest part of the compression of said spring meansand which suddenly increases said pressure to its final value during afinal relatively small fraction of the compression of said spring means.

4. In a machine, in combination, a drive shaft; support means supportingsaid drive shaft for rotation about its axis; a pulley coaxial with andfreely turnable with respect to said shaft; a stationary plate spacedfrom said pulley and surrounding said shaft; a first disc surroundingsaid shaft and having a side face directed toward and located adjacent aside face of said pulley, said first disc being located between saidpulley and plate; a first layer of a material of a high coefiicient offriction carried by one of said side faces; a second disc surroundingsaid shaft, located between said first disc and plate, and having a sideface directed toward and located adjacent a side face of said plate; asecond layer of a material of a high coefiicient of friction carried byone of the latter side faces; and a motion transmitting member connectedto said shaft for rotation therewith and for free axial movement withrespect thereto, said motion transmitting member being connected to saiddiscs for rotation therewith and for free axial movement with respectthereto and said motion transmitting member being located between saiddiscs and being operatively connected thereto for moving said first disctoward said pulley when said motion transmitting member moves towardsaid pulley and for moving said second disc toward said plate when saidmotion transmitting member moves toward said plate, whereby when saidmotion transmitting member moves toward said pulley a drive istransmitted from the latter to said shaft and when said motiontransmitting member is moved toward said plate the rotation of the shaftis braked.

5. In a skiving machine, in combination, a feed roll drive shaft fordriving a feed roll which feeds a workpiece with respect to a skiver;support means supporting said drive shaft for rotation about its axis; apulley eoaxial with and freely turnable with respect to said shaft;

9 a stationary. plate spaced from said pulley and surrounding saidshaft; a first disc surrounding said shaft and hav-v ing aside facedirected toward and located adjacent a side face of said pulley, saidfirst disc being located be: tween said pulley and plate; a first layerof a material of a'high coefficient of friction carried by one of saidside faces; a second disc surrounding said shaft, located betweensaidfirst disc and 'plate, and having a side face directed toward andlocated adjacent a side face of said plate; a second layer of a materialof a high coefi'icient of friction carried by one of the latter sidefaces; a motion transmitting member connected to said shaft for rotationtherewith and for free axial movement with respect thereto, said motiontransmitting member being connected to said discs for rotation therewithand for free axial movement with respect thereto and said motiontransmitting member being located between said discs and beingoperatively connected thereto for moving said first disc toward saidpulley when said motion transmitting member moves toward said pulley andfor moving said second disc toward said plate when said motiontransmitting member moves toward said plate, whereby when said motiontransmitting member moves toward said pulley a drive is transmitted fromthe latter to said shaft and when said motion transmitting member ismoved toward said plate the rotation of the shaft is braked; and springmeans cooperating with said discs and motion transmitting member forproviding the energy for urging said discs respectively toward saidpulley and'plate. I g g 6. In a skiving machine,'in combination, a feedroll drive shaft for driving a feed roll which feed-s a workpiece withrespect to a skiver; support means supporting said drive shaft forrotation about its axis; a pulley coaxial with and freely turnable withrespect to said shaft; a stationary plate spaced from said pulley andsurrounding said shaft; a first disc surrounding said shaft and having aside face directed toward and located adjacent a side faceof saidpulley, said first disc being located between said pulley and plate; afirst layer of a material of a high coefiicient of friction carriedbyone of said side faces; a seconddisc surrounding said shaft, locatedbetween said, firstdisc and plate, and having a side face directedtoward andlocated adjacent a side face of said plate; aflsecond layer ofamaterial of a high coefiicient offriction carried by one of the latterside faces; 'a motion transmittingmember connected to saidshaft forrotation therewith and fortfreeaxial movement with respect" thereto,said motion transmitting member being connected to said discs forrotation therewith and for free axial movement wi h: E PPE.FhfPfiQnfilliWfi: mot o nsmit ing member being located between saiddiscs and being operatively connected thereto for moving said first disctoward said pulley when said motion transmitting member moves towardsaid pulley and for moving said second disc toward said plate when saidmotion transmitting member moves toward said plate, whereby when saidmotion transmitting member moves toward said pulley a drive istransmitted from the latter to said shaft and when said motiontransmitting member is moved toward said plate the rotation of the shaftis braked; spring means 7 cooperating with said discs and motiontransmitting member for providing the energy for urging said discsrespectively toward said pulley and plate; and means capable of beingactuated by the operator of the machine and cooperating with said springmeans for controlling the latter to urge said discs selectively towardsaid pulley and plate, respectively.

7. In a machine as recited in claim 4, said shaft being formedintermediate its ends with a cutout through which said motiontransmitting member passes and said shaft being formed with an axialbore extending from an end thereof to said cutout and passing through apart of said shaft which is surrounded by said pulley; a leaf springlocated between said motion transmitting member and first disc andurging the latter away from said motion away from said plate; a push rodextending slidably' through said bore of said shaft, having one end inengagement with said leaf spring and having an opposite-end locatedbeyond said shaft; a bell crank pivotally carried by said support meansand having one arm which cooperates with said opposite end of said pushrod; a third spring stronger thanthe total of the forces of said leafspring and second spring cooperating with the other arm of said bellcrank for urging said one arm thereof toward said end of said shaft; andmeans capable of being actuated by the operator for turning said bellcrank against the influence of said third spring in a direction whichfrees said first and second discs to the influence of said leaf springand second spring, respectively, said third spring urging said fseconddisc toward said plate.

8. In a machine as recited in claim 7, said means capable of beingactuated by the operator including elon-' gated rod means of adjustablelength connected to said other arm of said bell crank and tiltable pedalmeans adapted to rest on the floor and operatively connected to saidelongated rod means for compressing the latter when said pedal means isactuated by theoperator to turn said bell crank against the force ofsaid third spring.

9. In a machine as recited in claim 8, releasable catch meanscooperating with said pedal means for maintaining thelatter in, an endposition where said discs are fully released to the; action of said leafspring and second spring, respectively.

10. In a machine -as recited in claim 4, said pulley surrounding saidshaft and the latter having a free threaded end portion located beyondsaid pulley on the side thereof opposite from said first disc, saidsecond disc having a, hub extending into said first disc andterminatingin an end face directed toward said pulley; a bearing carriedby said shaft and supporting said pulley for free rotation thereon, saidbearing having an inner race slidably engaging said shaft; a coil springsurrounding said shaft, bearing with one endtagainst said end face ofsaid hub, and bearing with its opposite end against an end face of saidinner race which is directed toward said hub; and a nutthreadedlyengaging said end portion of said shaft and bearing against an oppositeend face of said inner race which is directed away from said hub,whereby said spring "preventssaid nut from turning with respect to saidshaft during-rotation of the latter and whereby said nut maybe turnedwith respect to' said shaft to adjust theT distance'betWeen said pulleyand first disc. 11. IIna. machine, in combination, a drive shaft;support means supporting said drive shaft for rotation about its axis; apulley coaxial with and freely turnable'with respect to said shaft; adisc member and a block member coaxial with said shaft and being axiallyshiftable with respect to each other while constrained to rotatetogether, one of said members being axially shiftable with respect tosaid shaft while being constrained to rotate therewith, said disc memberhaving a side face directed toward and located adjacent a side face ofsaid pulley; a layer of material of a high coelficient of frictioncarried by one of said side faces so that when the other of said sidefaces presses against said layer the rotation of said pulley will betransmitted to said disc member so as to rotate said shaft; first springmeans operatively connected to said block member for urging the sametoward said pulley; second spring means located between and freelyabutting against said members, said second spring means being Weakerthan said first spring means and being increasingly compressed when saidfirst spring means moves said block member toward said pulley; andoperator controlled positioning means movable between a plurality ofpositions in which said position means is operatively connected to saidblock member for adjusting the distance of said block member from saidpulley against the force of said first spring means and an end positionin which said positioning means isdisconnected from said block memberand-frees the latter for movement against said pulley, whereby as long.as said positioning means is operatively connected to saidblock memberthe pressure of said other side face against said layer will be determinedonly by the extent to which said second spring means is compressed.

12. In a machine, in combination, a drive shaft; supportmeanssupportingsaid drive shaft for rotation about its axis; a pulley coaxialwith and freely turnable with respect to said shaft; a disc member andablock member coaxial with said shaft and being, axially shiftable withrespect to each other while constrainedto rotate together, one of saidmembers being axially shiftable with respect to said shaft while beingconstrained tolrotate therewith, said disc member havinga side facedirected toward and located adjacent a side faceof said pulley; a layerofmaterial of a high coefficient of friction carried by one of said sidefaces so that when the other of said side faces presses against saidlayer the rotation of. said pulley will be transmitted to said discmember so as to rotate said shaftyfirst spring means operativelyconnected to said block member for urging the same toward said. pulley;second spring means located between and freely abutting against saidmembers, said second spring meansbeing weaker than said first springmeans and being increasingly compressedwhen said firstispring meansmoves said block member'toward said'pulley; and operator controlledpositioning means movable in axial direction ofsaid shaft betweenaplurality of positions inwhich said position means is operativelyconnected to said block member for adjusting the'distance of said blockmember from said pulley against the force of said first spring meansand'an end position in which said positioning means is'disconnectedfromsaid block member and frees the latter for movement againstsaid'pulley, whereby as long as said positioning-means is operativelyconnectedto said block member the pressure of said other sideface'against said layer will be determined only by the extent to whichsaid secondspring means is compressed. V

13. In a machine, in combination, a drive shaft; supportmeans supportingsaid drive shaft for rotation about its axis; a-pulley' coaxial with andfreely turnable with respect to said shaft; a disc member andablockmember coaxial with said shaft andbeing axially shiftable with respecttoeach other while constrained to rotate together, one of said membersbeing axially shiftable with'respect to saidshaft whilebeing-constrained to rotate'therewith, said disc member having a sideface directedtoward and located adjacent a side face, of said pulley; alayer of mam 37a V material of a high coeflicientof friction carried byone of saidfside faces so that when theother of said side faces pressesagainst said layer the rotation of'said pulley-will be transmitted tosaiddisc member so as to rotate said shaft; first,spring meansoperatively connected to said bloclcmember for urging the same towardsaid pulley; second spring means located between and freely abuttingagainst said members, said second spring means being weaker than saidfirst spring means and being increasingly compressed when said firstspring means moves saidblock member toward said pulley, said secondspring.

means being in the form of a leaf spring having a characteristic whichgradually increases the pressure of said other sidelface against saidlayer during the greatestpart of thecompression of said second springmeans and which suddenly increases said pressure to its final valueduring a final relative smaller fraction of said compression; andoperator controlled positioning means movable between a plurality ofpositions in which said position means is operatively connected to saidblock memberfor adjusting the distance of said block member from saidpulley against the force of said first spring means and an end positionin which said positioning means is disconnected from said block memberand frees the latter for movement against said pulley, whereby as longas said positioning means is operatively connected to said block memberthe pressure of said other side face against said layer will bedetermined only by the extent to which said second spring means iscompressed.

References Cited in the file of this patent UNITED STATES PATENTS654,964 Ferres July 31, 1900 1,038,560 Gay Sept. 17, 1912 1,382,133Spencer et a1. June 21, 1921 1,643,356 Wade et al. Sept. 27, 19272,170,920 Boecker Aug. 29, 1939 2,201,581 Hallden May 21, 1940 2,219,139Nutt' Oct. 22,1940 2,503,476 Glover Apr. 11, 1950 2,706,545 Voight Apr.19, 1955 2,734,571 Mar-tell Feb. 14, 1956 2,739,680 Turner Mar. 27, 19562,757,766 McCroskey' Aug. 7, 1956 2,768,692. Engel Oct. 30, 19562,827,990 Hunt Mar. 25, 1958 FOREIGN PATENTS 945,201 Germany July 5,1956

